1. Rocks and Weathering

2. Which mountain range is older?
The Sierras are rocky and steep, higher than the Appalachians.
The Appalachians are more rounded and gently sloping, and are covered with soil and plants.

3. Which mountain range is older?
The Sierras formed within the last 10 to 20 million years ago.
The Appalachians formed more than 250 million years ago.

4. Q: How can you tell that the Sierra Nevadas formed much more recently than the Appalachians?

5. How is Earth's surface shaped?
1. Weathering- the process that breaks down rock and other substances at Earth's surface.
2. Erosion- the transportation of sediment by wind, water, ice, or gravity.
weathering vs. erosion video

6. Q: What is the difference between weathering and erosion?

7. The principle of uniformitarianism
-an assumption that the same processes that operate today operated in the past.

8. Two Types of Weathering
Mechanical-
When rock is physically broken into smaller pieces.
Keep the same chemical composition.
Chemical-
The process that breaks down rock through chemical changes.

9. Is this the cause of mechanical or chemical weathering?
Plant growth

10. Is this the cause of mechanical or chemical weathering?
oxidation

11. Is this the cause of mechanical or chemical weathering?
weak acid from plant roots or lichens

12. Is this the cause of mechanical or chemical weathering?
freezing and thawing

13. Ice wedging 1st - water seeps into cracks of rocks 2nd- water freezes
3rd - water expands when it freezes and breaks rock

14. Is this the cause of mechanical or chemical weathering?
pressure release

15. The causes of mechanical weathering
freezing and thawing
release of pressure
plant growth
actions of animals
abrasion

16. The causes of chemical weathering
water dissolves minerals
oxygen combines with iron in the presence of water forms rust (oxidation)
carbon dioxide dissolves in water to form carbonic acid
living organisms- root tips and lichens can form weak acid
acid rain is formed when pollutants combine with water vapor

17. What determines how fast weathering occurs?
surface area
type of rock
climate

18. Increasing the surface area of rock increases the rate of a chemical reaction

19. Q. Which type of stone weathers faster?
granite
marble - dissolves in acid, and is more permeable

20. Climate
Weathering is faster in hot and wet climate.